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Date: Wed, 23 Jan 2019 14:27:25 -0300
From: Paul Cercueil <paul@...pouillou.net>
To: Mathieu Malaterre <malat@...ian.org>
Cc: Thierry Reding <thierry.reding@...il.com>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ralf Baechle <ralf@...ux-mips.org>,
Paul Burton <paul.burton@...s.com>,
James Hogan <jhogan@...nel.org>,
Jonathan Corbet <corbet@....net>,
Ezequiel Garcia <ezequiel@...labora.co.uk>,
PrasannaKumar Muralidharan <prasannatsmkumar@...il.com>,
linux-pwm@...r.kernel.org,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
linux-watchdog@...r.kernel.org, linux-mips@...r.kernel.org,
linux-doc@...r.kernel.org, linux-clk@...r.kernel.org, od@...c.me,
Maarten ter Huurne <maarten@...ewalker.org>
Subject: Re: [PATCH v8 05/26] clocksource: Add driver for the Ingenic JZ47xx
OST
(re-send, in plain text this time, sorry for those who got it twice)
Le mer. 23 janv. 2019 à 9:58, Mathieu Malaterre <malat@...ian.org> a
écrit :
> On Wed, Dec 12, 2018 at 11:09 PM Paul Cercueil <paul@...pouillou.net>
> wrote:
>>
>> From: Maarten ter Huurne <maarten@...ewalker.org>
>>
>> OST is the OS Timer, a 64-bit timer/counter with buffered reading.
>>
>> SoCs before the JZ4770 had (if any) a 32-bit OST; the JZ4770 and
>> JZ4780 have a 64-bit OST.
>>
>> This driver will register both a clocksource and a sched_clock to
>> the
>> system.
>>
>> Signed-off-by: Maarten ter Huurne <maarten@...ewalker.org>
>> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
>> ---
>>
>> Notes:
>> v5: New patch
>>
>> v6: - Get rid of SoC IDs; pass pointer to ingenic_ost_soc_info
>> as
>> devicetree match data instead.
>> - Use device_get_match_data() instead of the of_* variant
>> - Handle error of dev_get_regmap() properly
>>
>> v7: Fix section mismatch by using
>> builtin_platform_driver_probe()
>>
>> v8: builtin_platform_driver_probe() does not work anymore in
>> 4.20-rc6? The probe function won't be called. Work around
>> this
>> for now by using late_initcall.
>>
>> drivers/clocksource/Kconfig | 8 ++
>> drivers/clocksource/Makefile | 1 +
>> drivers/clocksource/ingenic-ost.c | 215
>> ++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 224 insertions(+)
>> create mode 100644 drivers/clocksource/ingenic-ost.c
>>
>> diff --git a/drivers/clocksource/Kconfig
>> b/drivers/clocksource/Kconfig
>> index 4e69af15c3e7..e0646878b0de 100644
>> --- a/drivers/clocksource/Kconfig
>> +++ b/drivers/clocksource/Kconfig
>> @@ -648,4 +648,12 @@ config INGENIC_TIMER
>> help
>> Support for the timer/counter unit of the Ingenic JZ SoCs.
>>
>> +config INGENIC_OST
>> + bool "Ingenic JZ47xx Operating System Timer"
>> + depends on MIPS || COMPILE_TEST
>> + depends on COMMON_CLK
>> + select INGENIC_TIMER
>> + help
>> + Support for the OS Timer of the Ingenic JZ4770 or similar
>> SoC.
>> +
>> endmenu
>> diff --git a/drivers/clocksource/Makefile
>> b/drivers/clocksource/Makefile
>> index 7c8f790dcf67..7faa8108574a 100644
>> --- a/drivers/clocksource/Makefile
>> +++ b/drivers/clocksource/Makefile
>> @@ -75,6 +75,7 @@ obj-$(CONFIG_ASM9260_TIMER) +=
>> asm9260_timer.o
>> obj-$(CONFIG_H8300_TMR8) += h8300_timer8.o
>> obj-$(CONFIG_H8300_TMR16) += h8300_timer16.o
>> obj-$(CONFIG_H8300_TPU) += h8300_tpu.o
>> +obj-$(CONFIG_INGENIC_OST) += ingenic-ost.o
>> obj-$(CONFIG_INGENIC_TIMER) += ingenic-timer.o
>> obj-$(CONFIG_CLKSRC_ST_LPC) += clksrc_st_lpc.o
>> obj-$(CONFIG_X86_NUMACHIP) += numachip.o
>> diff --git a/drivers/clocksource/ingenic-ost.c
>> b/drivers/clocksource/ingenic-ost.c
>> new file mode 100644
>> index 000000000000..cc0fee3efd29
>> --- /dev/null
>> +++ b/drivers/clocksource/ingenic-ost.c
>> @@ -0,0 +1,215 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * JZ47xx SoCs TCU Operating System Timer driver
>> + *
>> + * Copyright (C) 2016 Maarten ter Huurne <maarten@...ewalker.org>
>> + * Copyright (C) 2018 Paul Cercueil <paul@...pouillou.net>
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/clocksource.h>
>> +#include <linux/mfd/ingenic-tcu.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pm.h>
>> +#include <linux/regmap.h>
>> +#include <linux/sched_clock.h>
>> +
>> +#include "ingenic-timer.h"
>> +
>> +#define TCU_OST_TCSR_MASK 0xc0
>> +#define TCU_OST_TCSR_CNT_MD BIT(15)
>> +
>> +#define TCU_OST_CHANNEL 15
>> +
>> +struct ingenic_ost_soc_info {
>> + bool is64bit;
>> +};
>> +
>> +struct ingenic_ost {
>> + struct regmap *map;
>> + struct clk *clk;
>> +
>> + struct clocksource cs;
>> +};
>> +
>> +static u64 notrace ingenic_ost_read_cntl(void)
>> +{
>> + /* Bypass the regmap here as we must return as soon as
>> possible */
>> + return readl(ingenic_tcu_base + TCU_REG_OST_CNTL);
>> +}
>> +
>> +static u64 notrace ingenic_ost_read_cnth(void)
>> +{
>> + /* Bypass the regmap here as we must return as soon as
>> possible */
>> + return readl(ingenic_tcu_base + TCU_REG_OST_CNTH);
>> +}
>> +
>> +static u64 notrace ingenic_ost_clocksource_read(struct clocksource
>> *cs)
>> +{
>> + u32 val1, val2;
>> + u64 count, recount;
>> + s64 diff;
>> +
>> + /*
>> + * The buffering of the upper 32 bits of the timer prevents
>> wrong
>> + * results from the bottom 32 bits overflowing due to the
>> timer ticking
>> + * along. However, it does not prevent wrong results from
>> simultaneous
>> + * reads of the timer, which could reset the buffer
>> mid-read.
>> + * Since this kind of wrong read can happen only when the
>> bottom bits
>> + * overflow, there will be minutes between wrong reads, so
>> if we read
>> + * twice in succession, at least one of the reads will be
>> correct.
>> + */
>> +
>> + /* Bypass the regmap here as we must return as soon as
>> possible */
>> + val1 = readl(ingenic_tcu_base + TCU_REG_OST_CNTL);
>> + val2 = readl(ingenic_tcu_base + TCU_REG_OST_CNTHBUF);
>> + count = (u64)val1 | (u64)val2 << 32;
>> +
>> + val1 = readl(ingenic_tcu_base + TCU_REG_OST_CNTL);
>> + val2 = readl(ingenic_tcu_base + TCU_REG_OST_CNTHBUF);
>> + recount = (u64)val1 | (u64)val2 << 32;
>> +
>> + /*
>> + * A wrong read will produce a result that is 1<<32 too
>> high: the bottom
>> + * part from before overflow and the upper part from after
>> overflow.
>> + * Therefore, the lower value of the two reads is the
>> correct value.
>> + */
>> +
>> + diff = (s64)(recount - count);
>> + if (unlikely(diff < 0))
>> + count = recount;
>> +
>> + return count;
>> +}
>> +
>> +static int __init ingenic_ost_probe(struct platform_device *pdev)
>> +{
>> + const struct ingenic_ost_soc_info *soc_info;
>> + struct device *dev = &pdev->dev;
>> + struct ingenic_ost *ost;
>> + struct clocksource *cs;
>> + unsigned long rate, flags;
>> + int err;
>> +
>> + soc_info = device_get_match_data(dev);
>> + if (!soc_info)
>> + return -EINVAL;
>> +
>> + ost = devm_kzalloc(dev, sizeof(*ost), GFP_KERNEL);
>> + if (!ost)
>> + return -ENOMEM;
>> +
>> + ost->map = dev_get_regmap(dev->parent, NULL);
>> + if (!ost->map) {
>> + dev_err(dev, "regmap not found\n");
>> + return -EINVAL;
>> + }
>> +
>> + ost->clk = devm_clk_get(dev, "ost");
>> + if (IS_ERR(ost->clk))
>> + return PTR_ERR(ost->clk);
>> +
>> + err = clk_prepare_enable(ost->clk);
>> + if (err)
>> + return err;
>> +
>> + /* Clear counter high/low registers */
>> + if (soc_info->is64bit)
>> + regmap_write(ost->map, TCU_REG_OST_CNTL, 0);
>> + regmap_write(ost->map, TCU_REG_OST_CNTH, 0);
>> +
>> + /* Don't reset counter at compare value. */
>> + regmap_update_bits(ost->map, TCU_REG_OST_TCSR,
>> + TCU_OST_TCSR_MASK, TCU_OST_TCSR_CNT_MD);
>> +
>> + rate = clk_get_rate(ost->clk);
>> +
>> + /* Enable OST TCU channel */
>> + regmap_write(ost->map, TCU_REG_TESR, BIT(TCU_OST_CHANNEL));
>> +
>> + cs = &ost->cs;
>> + cs->name = "ingenic-ost";
>> + cs->rating = 320;
>> + cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
>> +
>> + if (soc_info->is64bit) {
>> + cs->mask = CLOCKSOURCE_MASK(64);
>> + cs->read = ingenic_ost_clocksource_read;
>> + } else {
>> + cs->mask = CLOCKSOURCE_MASK(32);
>> + cs->read = (u64 (*)(struct clocksource
>> *))ingenic_ost_read_cnth;
>
> The function is declared as ingenic_ost_read_cnth(void), are you sure
> this is going to work ?
Hence the cast. The clocksource pointer passed as the first argument
will
simply be ignored by the function. This works fine.
>> + }
>> +
>> + err = clocksource_register_hz(cs, rate);
>> + if (err) {
>> + dev_err(dev, "clocksource registration failed:
>> %d\n", err);
>> + clk_disable_unprepare(ost->clk);
>> + return err;
>> + }
>> +
>> + /* Cannot register a sched_clock with interrupts on */
>> + local_irq_save(flags);
>> + if (soc_info->is64bit)
>> + sched_clock_register(ingenic_ost_read_cntl, 32,
>> rate);
>> + else
>> + sched_clock_register(ingenic_ost_read_cnth, 32,
>> rate);
>> + local_irq_restore(flags);
>> +
>> + return 0;
>> +}
>> +
>> +#ifdef CONFIG_PM_SLEEP
>> +static int ingenic_ost_suspend(struct device *dev)
>> +{
>> + struct ingenic_ost *ost = dev_get_drvdata(dev);
>> +
>> + clk_disable(ost->clk);
>> + return 0;
>> +}
>> +
>> +static int ingenic_ost_resume(struct device *dev)
>> +{
>> + struct ingenic_ost *ost = dev_get_drvdata(dev);
>> +
>> + return clk_enable(ost->clk);
>> +}
>> +
>> +static SIMPLE_DEV_PM_OPS(ingenic_ost_pm_ops, ingenic_ost_suspend,
>> + ingenic_ost_resume);
>> +#define INGENIC_OST_PM_OPS (&ingenic_ost_pm_ops)
>> +#else
>> +#define INGENIC_OST_PM_OPS NULL
>> +#endif /* CONFIG_PM_SUSPEND */
>> +
>> +static const struct ingenic_ost_soc_info jz4725b_ost_soc_info = {
>> + .is64bit = false,
>> +};
>> +
>> +static const struct ingenic_ost_soc_info jz4770_ost_soc_info = {
>> + .is64bit = true,
>> +};
>> +
>> +static const struct of_device_id ingenic_ost_of_match[] = {
>> + { .compatible = "ingenic,jz4725b-ost", .data =
>> &jz4725b_ost_soc_info, },
>> + { .compatible = "ingenic,jz4770-ost", .data =
>> &jz4770_ost_soc_info, },
>> + { }
>> +};
>> +
>> +static struct platform_driver ingenic_ost_driver = {
>> + .driver = {
>> + .name = "ingenic-ost",
>> + .pm = INGENIC_OST_PM_OPS,
>> + .of_match_table = ingenic_ost_of_match,
>> + },
>> +};
>> +
>> +/* FIXME: Using device_initcall (or buildin_platform_driver_probe)
>> results
>> + * in the driver not being probed at all. It worked in 4.18...
>> + */
>> +static int __init ingenic_ost_drv_register(void)
>> +{
>> + return platform_driver_probe(&ingenic_ost_driver,
>> + ingenic_ost_probe);
>> +}
>> +late_initcall(ingenic_ost_drv_register);
>> --
>> 2.11.0
>>
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